// ###第二层中间件###
// koa_response_header.js 是用来专门设置响应头的中间件
module.exports = async (ctx, next) => {
  const contentType = 'application/json; charset=utf-8';
  ctx.set('Content-Type',contentType);
  // ***允许跨域***
  ctx.set("Access-Control-Allow-Origin", "*")
  ctx.set("Access-Control-Allow-Methods", "OPTIONS, GET, PUT, POST,DELETE")

  await next();
}